Antiglitches in accreting pulsars from superfluid vortex avalanches

Three sudden spin-down events, termed `anti-glitches', were recently discovered in the accreting pulsar NGC 300 ULX-1 by \textit{Neutron Star Interior Composition Explorer} (NICER) mission. Unlike previous anti-glitches detected decelerating magnetars, these are first recorded an accelerating pulsar. One standard theory is that spin-up glitches caused avalanches of collectively unpinning vortices transfer angular momentum from superfluid interior to crust a neutron star. Here we test whether vortex also consistent with ULX-1, reversed. We perform $N$-body simulations up $5 \times 10^{3}$ pinned two dimensions secularly and containers. Vortex routinely occur both scenarios, propagating inwards outwards respectively. The implications for observables, such as size waiting time statistics, considered briefly.